Elmarit-M 90mm front focus problem

[Torpille]

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hello,
 
I have recently acquired on the internet an elmarit-m 90 mm in mint condition. 
The seller has had it for 25 years and has used it very little with his M5.

I mount it on the M Digital and... all the pictures are blurred when I focus with the Messucher.
Front focus of a few centimeters...

I do the tests with the live view and no worries the photos are sharp. 

To go from blur with the Messucher to sharp with the live view, I have to turn the focus ring by 3 mm.

Luckily I used the second identical lens of a friend and there surprise all is sharp !

I specify that the 2 lenses are not coded and the tests are done at F:2,8

According to you which technical solution is offered to me ?

Cheers

 

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[Fgcm]

Send it to Leica or an independent lab. it’s an easy fix. They will change the shims between the optical group and the focusing group. Sounds complicated, but it is not. 

The Elmarit M 90 is one of the best 90 ever. Worth it having it fixed.

Edited December 19, 2020 by Fgcm

[lct]

Yes it just needs to be calibrated for digital. Happened to mine too. Easy fix.

[adan]

It happens. I bought a 90mm Summicron (1980 vintage) last spring, and on digital it revealed a tendency to back-focus. Sent it in for adjustment (and 6-bit coding). Performs great now.

- Lenses do need adjustment sometimes.

- Lenses built before 2004 or so - i.e. for film - usually were built to somewhat looser tolerances, simply because the tolerances for the film image plane were not as tight, so there was no point. If the position of the film can vary by 0.01 mm, there is no use adjusting the lens to 0.001mm (weakest link theory).

Film had a built-in leeway with a 10-micron-thick emulsion; film base thicknesses varied from maker to maker and era to era (celluloid, acetate, Estar); the film gelatin coating (and the incorporated silver molecules) tended to diffuse resolution a bit (one reason the 90mm Elmarit-M had an excellent reputation is its higher edge contrast (MTF), which tends to burn through the emulsion diffusion and produce cleaner edges to light/dark boundaries).

Digital's infinitely-thin "dimensionless" image plane requires tighter tolerances - one reason Leica built their "new" Wetzlar factory.

[farnz]

Just a thought ... you've said that the seller had used it for 25 years so I wondered whether it's a version 1 (11029, 11129 or 11026) where the lens cell can be unscrewed to use it on a Visoflex II or III (with a 16072 and 16464).  If so, it might simply be that the lens cell has started to unscrew and needs tightening, which would save a trip to Wetzlar.

If it is the version 2 (11807, 11808, or 11809) then please ignore the above because the lens cell can't be unscrewed.

Pete.

[epand56]

22 hours ago, lct said:

Yes it just needs to be calibrated for digital. Happened to mine too. Easy fix.

Mine too needed to be calibrated (not rare when you have to use them on a digital camera). After that was spot on. While out for calibration I also had it 6bit coded. 

[lct]

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So did i. Same for a 90/2 v3 BTW but my 90/2 v2, 90/2.8 v1 and "thin" 90/2.8 are still spot on. I use them less and less on rangefinders though to be honest.